The nano-virus works by intelligently adapting itself to the species that it has infected. After that it is simply a matter of time before it finds the right trigger to kill the entire species outright.[2]

Around the time of the First Shadow War, the Shadows attacked another unnamed planet when they refused to allow a base to be built on their world. The Shadows released a strain of the same plague that later infected Earth. The people of this planet studied the plague virus for three years before deciding to put their entire race into suspended animation. One person was brought out of suspended animation to take care of the machines and continue the tests on the aliens. 500 people had died in that service by 2267.[3]

In December 2266, at the onset of the Drakh War, Earth was infected with the plague by the Drakh in an act of spite after their attempt to destroy the planet with a Death Cloud was thwarted.[1] The Drakh had originally intended to use the plague on Minbar after deploying the Death Cloud against Earth.[4]

Earth was placed under a quarantine for several years before a cure was finally discovered and by 2271, the plague had been completely eradicated. Following the plague, Earth Alliance officials continued some of the quarantine policies that had been enacted, fearing another such biological disaster would be visited upon Earth if they did not carefully scrutinize individuals visiting Earth.[8]